1. Field of the Invention
The present invention relates to a vehicle headlamp which is so-called a projector type headlamp.
2. Related Art
Generally, a vehicle headlamp of a projector type is constituted such that a projection lens is arranged on an optical axis extended in a longitudinal direction of a vehicle, a light source is arranged on a side rearward from a rear focal point thereof, and light from the light source is reflected to be proximate to the optical axis by a reflector.
Disclosed in JP-A-2004-127830 is a vehicle headlamp of a projector type in which a light source thereof is constituted as a line segment light source extended in a vehicle width direction.
Further, disclosed in JP-A-2000-348508 is a vehicle headlamp of a projector type including a mirror member having an upward directed reflecting face extended from a vicinity of a rear focal point of a projection lens to a rear side such that a portion of reflected light from a reflector thereof is reflected to an upper side.
When the vehicle headlamp constituting the light source by the line segment light source extended in the vehicle width direction is adopted as described in JP-A-2004-127830, an inverted projected image of the light source formed by the projection lens can be constituted by an image substantially in a transversely prolonged rectangular shape extended to be long in a horizontal direction and therefore, a transversely prolonged light distribution pattern having a small nonuniformity in light distribution can easily be formed. Further, when constituted in this way, there can easily be constructed a constitution in which a light source bulb is inserted to be fixed by the reflector from a side direction of the optical axis, thereby, a front and rear length of a lamp piece can be shortened to achieve thin-sized formation thereof.
Further, when the vehicle headlamp including the mirror member as described in JP-A-2000-348508 is adopted, a light distribution pattern having a clear cut off line as an inverted projected image of a front end edge of the upward directed reflecting face at an upper end portion thereof can be formed and reflected from the reflector can effectively be utilized as a front irradiating light.
However, according to the vehicle headlamps described in JP-A-2004-127830 and JP-A-2000-348508, a solid angle of a reflecting face of the reflector relative to the light source cannot be increased so much and therefore, a problem that there is a limit in increasing an efficiency of utilizing a light flux of the light source is posed.